Torsion Bar Suspension for p38 type Lakester

[tpotts]

In my initial review of lakester suspension,  I have come to the conclusion (right or wrong) that a  front & rear suspension (non rigid)  would be beneficial at both Maxton & Bonni ville. Looking at cost,  size, number of components, aerodynamics,  simplicity etc.  It is my thought that a torsion bar approach might be best. Having no experience in this area,  I would appreciate any comments on this type of suspension, from those who have considered it or are currently using this type. I am interested in effectiveness, cost, possible off the counter components, design parameters etc?  As planned the fiberglass body will be approx 16ft  length and 36" in diameter.  The first engine will probably be a modified model b,  at a later date,  I plan to expand to something with more power.  Thanks for your time and consideration.  Best Tom

[Rex Schimmer]

Tom,
If this works I am attaching a pic. of Steve Nelson's new lakester that uses torsion bar front suspension. Steve uses VW torsion bars, actually laminated rubber and steel bars, and then makes a very straight forward connection to his front axle and the torsion bar arm is also used to locate the axle.

Steve is really busting ass at trying to get ready for August, he has the frame powder coated, bright orange and boy is it pretty!! and he is now hustling to get a motor together.

Rex

[Sumner]

First Tom I accidently deleted your PM and forgot it, so glad you posted.  I'll try and get back to you tomorrow when I have more time.

Rex, that looks to be a nice car.  I looked at torsion bars for my car, but couldn't figure them out.  I was looking in Speedway's midget and sprint car catalogs and couldn't figure out how to pick something for a certain rate.  The coil spring rates were something I understood better.

On that car I would imagine the torsion bar is controlling the ride height.  I know on some bars you can adjust the ride height by turning the bars up or down, but does that also affect the spring rate?  On this car if he is using the VW ones is he stuck with only one spring rate?

c ya, Sum

[Rex Schimmer]

Torsion bars are like coil springs, ( actually coil springs is a small torsion bar that is formed into a coil.) if you twist them they will raise or lower the car but will not change rate, if you happen to run them against a stop and then screw in some preload it will feel like you have increased the rate but really you have just increased the point at which an increasing load will make the bar (or coil spring) start to deflect.

Using the VW torsion bars does limit the rate selection although you can shorten or lengthen them to change the rate also you can shorten or lengthen the torsion bar arm to change the rate.

Rex

[interested bystander]

Mark Williams Enterprises has a funny car/altered bar  and a  a front motor dragster bar like used in the '60s. Similiar to the VW based bar Rex posted
The F/C bar has about a 900lb/inch rate with I think 6" arms and is 26" wide- the F/M Dragster I ain't sure of. Williams has an online catalog

Does one need to provide shocks for same??

[Reverend Hedgash]

John Lynch's Belly Tank ran over 300mph on Lake Gairdner in 2005.

It has a torsion bar setup and seems to work well for him.  

My thoughts  on torsion bar set ups is they are appealling because of their simplicity, there's a lot of knoweledge and parts available from speedway, and there is very little in the wind. (Especially when comparing with the front end of the So-Cal Belly Tank!)

See photo's below for John Lynches set up.

rH+

Rex, Steve's car looks a fine piece of work. Where can I find more info and photos?

[gazza414]

I remember that RH.... the salt was dry toooooooo and hard.

[Rex Schimmer]

Per the rule book you must have a shock for ever suspended wheel, if you look close on the picture of Steve Nelson's car that I posted you can see one of the two shocks that Steve has mounted inside the body and connected to the front axle. On the dragster type that Mark Williams markets they use a friction pad between the arm and the torsion bar housing that provides dampening. I personally like oil shocks as they are velocity sensitive and don't need constant adjustment like friction shocks.

Rex

[Tom Simon]

I build and dragrace aircooled VW's with stock-type torsion bar suspensions. I've also been around sprint cars for a while, a couple friends race 360's here in Northern California. the classic design is torsion bar on all four corners, simple, adjustable and it works. Unlike with coil overs, the shock mount can be made from lighter stock. In fact, when going through Summer's lakester build site last night, the rear suspension seemed to be heading down the sprint-torsion bar path  (I still like the way it came out, very nice stuff). The probem I see with most inboard suspensions is that every pivot point carry the load of the corner of the car, and must be made in such a way as to carry those loads at the angles designed in. It just seems to get complicated in a hurry, at least to me. Case an point the SoCal belly tank car, and any Indy or open wheel Formula car.

OEM VW bars were made in three lengths and 3 or 4 diameters starting at about 21mm dia. The Bug Pack catalog has a good OEM reference chart in the front of it. The offroaders still use torsion bars, particularly in the classes that still require stock-type torsion suspension, so aftermarket bars are readily available up to 30mm dia, and relatively cheap ($180/pair?) through Sway-A-Way or Bug Pack distributors like Aircooled.net

My high school friend's '65 Mopar had dual A-arm front suspension with torsion bars from the factory. Raising and lowering the front end was a breeze on that ole hot rod. Lack of coil springs up front also made room for a fat Hemi     I wish I had a picture, but the torsion bar was attached to the lower A-arm with splines right at the pivot point. It ran rearward under both frame rails, through a tube, and used a dog and set-adjuster screw like a spint car.